The preparation of .alpha.-keto-carboxylic acids and their derivatives has been the subject of a large number of investigations. According to Rodd, The Chemistry of Carbon Compounds (1952 edition), Vol. 1, pages 227-229, the following methods of preparation are available:
gentle oxidation of .alpha.-hydroxyacids containing a secondary hydroxyl group, or by the enzymatic deamination of .alpha.-amino-acids; PA1 hydrolysis of an acyl cyanide; PA1 hydrolysis of .alpha.-oximino-esters; PA1 from glycidic acid esters on treatment with benzene saturated with boron trifluoride; PA1 from .alpha.,.beta.-dibromocarboxylic acids by forming a piperidine addition compound followed by hydrolysis; PA1 from .alpha.-keto-acetals by ultraviolet irradiation in the presence of N--bromosuccinimide; PA1 from .alpha.-bromomethylketones by boiling with selenium dioxide in absolute methanol or ethanol; PA1 from carboxylic acid esters by oxidation with selenium dioxide; PA1 permanganate oxidation of vinyl ketones; PA1 from carboxylic acid esters by condensation with oxalic ester followed by decarboxylation; PA1 from aldehydes via 5-alkylidene-2-thio-oxazolid-4-ones or by reaction with methyl methoxyacetate; hydrolysis of azlactones or acetamido-acrylic acids; hydrolysis of the reaction product of Grignard reagents on diethyl-oxamic ester; PA1 oxidation of .alpha.-hydroxyacid esters containing two .beta.-hydrogen atoms by N--boromosuccinimide in carbon tetrachloride to .beta.-bromo-.alpha.-keto-acid esters; and by the action of alkali on the dimethanesulphonates and ditoluene-p-sulphonates of .alpha.,.beta.-dihydroxy-carboxylic acids.
Methods for preparing arylpyruvic acids also are known. For example, U.S. Pat. No. 4,152,352 discloses the preparation of an arylpyruvic acid by reacting an arylmethyl halide in a liquid solvent medium with carbon monoxide at pressures 5 to 200 bars in the presence of a catalytic amount of a metal carbonyl compound and an alkaline earth metal inorganic base. Further, U. K. patent application No. 2,026,478A discloses that alkali metal salts of an arylpyruvic acid can be prepared by reacting an arylmethyl halide, carbon monoxide and an alkali metal base in the presence of a metal carbonyl compound as catalyst and in the presence of an alcohol or cyclic ether as solvent.
In co-pending U.S. application Ser. No. 353,440, entitled "PROCESS FOR PREPARING ARYLALKYPYRUVIC ACIDS," filed Mar. 1, 1982, there is disclosed a method of preparing certain arylalkypyruvic acids by carbonylating a suitable arylalky halide in a liquid solvent medium with carbon monoxide at elevated temperature and pressure in the presence of a metal carbonyl compound and an alkali or an alkaline earth metal inorganic base. Further, in co-pending U.S. Application Serial No. 353,473, entitled "PROCESS FOR PREPARING ALKYL ALPHA-KETO-CARBOXYLIC ACIDS FROM ALKYL HALIDES," filed Mar. 1, 1982, the preparation of alkyl-.alpha.-keto-carboxylic acids by reacting a primary alkyl halide in a liquid solvent medium with carbon monoxide in the presence of a catalytic amount of a metal carbonyl and an inorganic base is disclosed. Still further, in co-pending U.S. Application Serial No. U.S. Ser. No. 405,817, entitled "PROCESS FOR PREPARING .beta.-SUBSTITUTED-.alpha.-KETO-CARBOXYLIC ACIDS," filed Aug. 6, 1982, there is disclosed the preparation of .beta.-substituted-.alpha.-keto-carboxylic acids by reacting a secondary halide with carbon monoxide in the presence of a metal carbonyl catalyst and an inorganic base.
The cobalt-catalyzed carbonylation of secondary benzyl halides to give either monocarbonyl or double carbonyl insertion or coupling of organic halides is reported by E. Francalanci et. al., Journal of Electroanalytical Chemistry, 1982, pp. 59-70.